Tammy Duckworth

Gretchen Whitmer (I think she'll run for Senate if Stabenow retires)

J.B. Pritzker

Jay Inslee

Gina Raimnodo

Those are my suggestions. Klobuchar ran last time and got 75 votes. Harris won't run. Bernie's too old and so is Warren. If Democrats keep control of the House, Biden won't run. If the GOP/POT takes over, he'll run.